Osteology (Part 5): Metatarsals & Phalanges Flashcards
Metatarsals absolute length
- Longest to shortest
- 2 > 3 > 5 > 4 > 1
Metatarsals distal projection in articulated foot
- Farthest to nearest
- 2 > 3 > 1 > 4 > 5
- OR
- 2 > 1 > 3 > 4 > 5
Metatarsals articulate proximally with
- Cuneiforms
- Cuboid
- Forms tarsometatarsal (Lisranc’s) joint
Metatarsals contribute to
- Transverse arch
- Both medial/lateral longitudinal arches
Metatarsals are flexed with bases being
- Elevated
- Different heights (2nd is the highest)
- Metatarsal heads are in the same plane
1st metatarsal diverges from the 2nd forming
- Intermetatarsal angle
Ray
- Cuneiforms + associated metatarsals for 1-3
- Just metatarsals for 4,5
- Some people include phalanges
Metatarsal bases articulate with
- Cuneiforms
- Cuboid
- Neighboring metatarsals
1st metatarsal shape
- Kidney bean shaped
2nd metatarsal shape
- Wedge (triangle) shaped
- Apex inferior
3rd metatarsal shape
- Wedge (triangle)
- Apex inferior
4th metatarsal shape
- Quadrilateral
5th metatarsal shape
- Triangular
- Apex lateral
Metatarsal shaft
- Curved
- Convex dorsal
- Concave plantar
Metatarsal head (for the lesser metatarsals, 2-5)
- Oval (elliptical) shaped
- 1st has a few differences
Metatarsal head structures
- Articular cap (facet)
- Medial and lateral tubercles
Articular cap/facet (metatarsal heads 2-5)
- Anterior (distal) end
- Articulates with proximal phalanx of corresponding digit
- Forms MTP joint for that digit
- Extends further onto plantar surface
Medial and lateral tubercles (metatarsal heads 2-5)
- Ligament attachment
- Metatarsophalangeal ligaments (collateral ligaments)
- Metatarsophalangeal suspensory ligament (metatarsoglenoid ligament)
Metatarsal plantar surface structures
- Medial/lateral condyles
- Groove for flexor tendon
Medial and lateral condyles (metatarsal plantar surface)
- Weight-bearing surface
- Lateral is larger and longer and projects more proximal
Groove for flexor tendon (metatarsal plantar surface)
- Located between condyles
1st metatarsal
- Shortest and broadest metatarsal
- Very strong
1st metatarsal base surfaces
- Posterior
- Lateral
- Medial
1st metatarsal posterior surface
- Kidney shaped articular facet
- Articulates with medial cuneiform (tarsometatarsal joint)
1st metatarsal lateral surface
- Small oval facet for articulation with 2nd metatarsal (intermetatarsal joint)
- (not always present)
- Tuberosity of 1st metatarsal
Tuberosity of 1st metatarsal
- Located on the lateral base
- Junction of lateral and plantar surface
- Posterolateral projection for peroneus longus insertion
1st metatarsal medial surface
- 1st Metatarsal tubercle
- Junction of medial and plantar surface
- Attachment of tibialis anterior
1st metatarsal head
- Quadrilateral
- Distal articular facet
Distal articular facet (1st metatarsal head)
- Convex facet
- Articulates with proximal phalanx of hallux (1st MTP)
1st metatarsal head plantar surface structures
- Crista
- Medial/lateral condyles
Crista (1st metatarsal head plantar surface)
- Ridge from anterior articular surface to plantar surface
Medial and lateral condyles (1st metatarsal head plantar surface)
- Weight-bearing surfaces
- Grooves for articulation with medial and lateral sesamoids
1st metatarsal head has 3 articulations
- 1 with proximal phalanx
- 2 with sesamoids
Sesamoids in relation to 1st metatarsal head
- Lack bony attachment to 1st metatarsal
- Embedded in FHB and plantar plate
- Tight ligamentous attachment
2nd metatarsal
- Longest metatarsal
- Keystone for Lisfranc joint
- Base is wedge shaped, apex inferior
2nd metatarsal articulations
- All 3 cuneiforms (3 tarsometatarsal joints)
- Proximal phalanx base (2nd MTP)
- 3rd metatarsal base (intermetatarsal joint)
2nd metatarsal base structures
- Proximal triangular facet
- Oval articular facet
- 2 articular facets for lateral cuneiform and 3rd metatarsal
Proximal triangular facet (2nd metatarsal base)
- Articulates with 2nd cuneiform
Oval articular facet (2nd metatarsal base)
- Facet for medial cuneiform
- On posteriosuperior border of medial surface
2 Articular facets for lateral cuneiform and 3rd metatarsal (2nd metatarsal base)
- On lateral surface facet separated by a roughened ridge
- Vertical ridge separates distal (3rd metatarsal, intermetatarsal joint) and proximal (3rd cuneiform)
3rd metatarsal articulations
- Proximal phalanx base of 3rd toe (3rd MTP)
- 2nd and 4th metatarsal bases (2 intermetatarsal joint)
- 3rd cuneiform (tarsometatarsal joint)
3rd metatarsal base
- Wedge shaped
- Apex inferior
3rd metatarsal base structures
- Proximal triangular facet
- Oval articular facet for 4th metatarsal
- Articular facet for 2nd metatarsal
Proximal triangular facet (3rd metatarsal base)
- Articulates with 3rd cuneiform
Oval articular facet for 4th metatarsal (3rd metatarsal base)
- Posteriosuperior border of lateral surface
Articular facet for 2nd metatarsal (3rd metatarsal base)
- 2 demi-facets on medial surface, posterior edge
4th metatarsal articulations
- Base of 4th proximal phalanx base (4th MTP)
- 3rd and 5th metatarsal bases (2 intermetatarsal joints)
- 3rd cuneiform and cuboid (2 tarsometatarsal joints)
4th metatarsal base
- Quadrilateral in shape
4th metatarsal base structures
- Proximal quadrilateral articular facet
- Articular facet for lateral cuneiform and 3rd metatarsal
- Facet for 5th metatarsal
Proximal quadrilateral articular facet (4th metatarsal base)
- Articulation with cuboid
Articular facet for lateral (4th metatarsal base)
- Double facet on medial surface
- Proximal: lateral cuneiform
- Distal: 3rd metatarsal
Facet for 5th metatarsal (4th metatarsal base)
- Large facet on lateral surface
5th metatarsal articulations
- 5th proximal phalanx base (5th MTP)
- Cuboid (tarsometatarsal)
- Base of 4th metatarsal (intermetatarsal)
5th metatarsal base structures
- Proximal triangular articular facet
- Articular facet for 4th metatarsal
- Styloid process of 5th metatarsal (tuberosity of 5th metatarsal)
- Groove for abductor digiti minimi
Proximal triangular articular facet (5th metatarsal base)
- Articulates with cuboid
- Apex is lateral
Articular facet for 4th metatarsal (5th metatarsal base)
- Medial surface
Styloid process/tuberosity of 5th Metatarsal (5th metatarsal base)
- Large prominence
- Extends proximally and laterally
- Muscle and ligament attachment
- Very palpable
Groove for abductor digiti minimi (5th metatarsal base)
- Inferior aspect of styloid process
- Passage of ADM
Metatarsal blood supply
- Nutrient foramen point away from the growing end (growth plate)
- 1st metatarsal is angled distally
- 2-5 metatarsals are angled proximally
1st metatarsal blood supply
- Nutrient foramen on lateral surface, angled distally
- Supplied by 1st dorsal metatarsal artery
- Can be dual supply from dorsal and plantar metatarsal arteries with multiple nutrient foramina
2nd metatarsal blood supply
- Nutrient foramen on lateral shaft, angled proximally
- Nutrient artery from 2nd dorsal or plantar metatarsal artery
3rd metatarsal blood supply
- Nutrient foramen is on medial or lateral shaft, angled proximally
- Nutrient artery from 2nd or 3rd dorsal or plantar metatarsal artery
4th metatarsal blood supply
- Nutrient foramen on medial or lateral surface of shaft, angled proximally
- Nutrient artery is 3rd or 4th dorsal or plantar metatarsal artery
5th metatarsal blood supply
- Nutrient foramen on medial surface of shaft, angled proximally
- Nutrient artery from 4th plantar metatarsal artery
Phalanges
- Digits 2-5 have proximal, middle, and distal phalanges
- Digit 1 only has proximal and distal
- Phalanges consist of a base, shaft, and head
- Longitudinal grooves for flexor tendons on plantar surface
Proximal phalanges structures
- Proximal/distal articular surface (facet)
- Medial/lateral tubercle
Proximal articular surface/facet (proximal phalanges)
- Located at the base
- Round and concave
- Articulates with metatarsal heads
Distal articular surface/facet (proximal phalanges)
- Located at the head
- Convex
- Articulates with base of middle phalanges of digits 2-5 (or base of distal phalanx of the hallux)
Medial and lateral tubercles (proximal phalanges)
- Located at the medial/lateral plantar aspect of bases
- Metatarsophalangeal ligaments (collateral ligaments) insert at the bases
- Located at the dorsomedial and dorsolateral aspects of the heads
- Interphalangeal ligaments (collateral ligaments) attach at the heads
Middle phalanges structures (only digits 2-5)
- Proximal/distal articular surface
- Medial/lateral tubercles
Proximal articular surface (middle phalanges)
- Located at the base
- Concave
- Articulates with heads of proximal phalanges (2-5)
Distal articular surface (middle phalanges)
- Located at the head
- Convex
- Articulates with base of distal phalanges (2-5)
Medial and lateral tubercles (middle phalanges)
- Located at the medial/lateral plantar aspect of bases
- Located at the dorsomedial and dorsolateral aspects of the heads
- Ligament attachment
- Interphalangeal ligaments (collateral ligaments)
Distal phalanges (ungula phalanges)
- Smallest
- Shaped like a mushroom
- Flattened head (support nail plate)
Distal phalanges stuctures
- Proximal articular surface
- Medial/lateral tubercles
Proximal articular surface (distal phalange)
- Located at the base
- Concave
- Articulates with heads of middle phalanges (digits 2-5) and head of proximal phalanx (digits 1)
Medial and lateral tubercles (distal phalanges)
- Located at the medila/lateral plantar aspect of bases
- Ligament attachment
- Interphalangeal ligaments (collateral ligaments) at the heads
Most common symphalangism in the lower extremity
- Fusion of the middle and distal phalanges of the 5th digit